Study on N-fixing biofertilizer production with dry sludge from wastewater treatment process of Vietnam brewery limited

Abstract

The wastewater treatment processes of Vietnam Brewery Limited (VBL) generated about 6 ton/day dry sludge which it contains 1.86% total Nitrogen, 7.17% total phosphor, 0.108% Kali, 856.89 mg kg-1 Zn, 89.60 mg kg-1 Cu, 43.20 mg kg-1 Ni, 8.88 mg kg-1 Pb, 93.55 mg kg-1 Mn, 2.99 mg kg-1 Co, 2,800 mg kg-1 Fe, 200.46 mg kg-1 Cr.... This dry sludge can be used as a raw material to produce N-fixing biofertilizer is considered as a new alternative for recycling. Bacterial species: Rhizobium sp.: RH1, RH2, RH3, RH4 and Azotobacter sp. had been inoculated with the mixture of dry sludge and peat (3:1), Ao = 45%, pH = 7, room temperature, 40 ml/100g broth culture. The results showed that the cell count reached 2.37 × 109 cfu g-1, 2.9 × 109 cfu g-1, 3.65 × 109 cfu g-1, 2.77 × 109 cfu g-1, 6.18 × 109 cfu g-1, respectively. The quantity of cells per gram of inoculants in this experiment was lower in dry sludges than in peat based carrier. These new practices contribute in reducing the pollution load. Consequently, this can decrease the cost of sludge disposal and the cost of N-fixing biofertilizer production.